Identification of erythropoietin producing cells in fetal mouse liver cultures.

Fetal mouse liver explants were cultured and the culture media shown to possess an erythropoietically active substance neutralizable by antiserum to sheep plasma erythropoietin, suggesting that the media contain erythropoietin. Immunofluorescent and carbon particle ingestion techniques suggest that the erythropoietin was elaborated by macrophages or Kupffer cells of the hepatic reticuloendothelial system.